Mechanics of Respiration

Question 1

External respiration process

Answer 1

occurs between the lungs and blood. When a person inhales, alveoli fill with oxygen through diffusion

Oxygen content is much higher than carbon dioxide levels.

While in the alveoli region, blood becomes oxygen-rich.

Once oxygenated, the blood leaves the lungs and travels through the left side of the heart, where it is pumped into circulation

Question 2

Internal respiration process

Answer 2

• occurs between the blood and tissues
• Once blood enters circulation, it reaches the capillaries
• Oxygen diffuses through the capillaries into the cells
• Carbon dioxide diffuses from the cells into the capillaries
• Because carbon dioxide content is higher than oxygen content in blood at this point, it is called oxygen-poor blood
• oxygen-poor blood travels to the right side of the heart. It moves through the pulmonary circuit, where external respiration begins